The growing presence of artificial lighting across the globe presents a number of challenges to human and ecological health despite its societal benefits. Exposure to artificial light at night, a seemingly innocuous aspect of modern life, disrupts behavior and physiological functions. Specifically, light at night induces neuroinflammation, which is implicated in neuropathic and nociceptive pain states, including hyperalgesia and allodynia. Because of its influence on neuroinflammation, we investigated the effects of dim light at night exposure on pain responsiveness in male mice. In this study, mice exposed to four days of dim (5 lux) light at night exhibited cold hyperalgesia. Further, after 28 days of exposure, mice exhibited both cold hyperalgesia and mechanical allodynia. No heat/hot hyperalgesia was observed in this experiment. Altered nociception in mice exposed to dim light at night was concurrent with upregulated interleukin-6 and nerve growth factor mRNA expression in the medulla and elevated μ-opioid receptor mRNA expression in the periaqueductal gray region of the brain. The current results support the relationship between disrupted circadian rhythms and altered pain sensitivity. In summary, we observed that dim light at night induces cold hyperalgesia and mechanical allodynia, potentially through elevated neuroinflammation and dysregulation of the endogenous opioid system.

中文翻译：

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夜间微光照射会导致雄性小鼠出现冷痛觉过敏和机械异常性疼痛。

尽管人造照明具有社会效益，但全球范围内越来越多的人造照明对人类和生态健康提出了许多挑战。夜间暴露于人造光是现代生活看似无害的一个方面，但会扰乱行为和生理功能。具体来说，夜间光线会诱发神经炎症，这与神经病理性和伤害性疼痛状态有关，包括痛觉过敏和异常性疼痛。由于它对神经炎症的影响，我们研究了夜间昏暗光线对雄性小鼠疼痛反应的影响。在这项研究中，老鼠在夜间暴露于昏暗 (5 勒克斯) 光线下四天，表现出冷痛觉过敏。此外，在暴露 28 天后，小鼠表现出冷痛觉过敏和机械异常性疼痛。在这个实验中没有观察到热/热痛觉过敏。夜间暴露于昏暗光线下的小鼠的伤害感受改变与髓质中白细胞介素 6 和神经生长因子 mRNA 表达上调以及大脑导水管周围灰质区域 μ-阿片受体 mRNA 表达上调同时发生。目前的结果支持昼夜节律紊乱与疼痛敏感性改变之间的关系。总之，我们观察到夜间昏暗的光线会诱发冷痛觉过敏和机械异常性疼痛，这可能是通过神经炎症升高和内源性阿片系统失调引起的。目前的结果支持昼夜节律紊乱与疼痛敏感性改变之间的关系。总之，我们观察到夜间昏暗的光线会诱发冷痛觉过敏和机械异常性疼痛，这可能是通过神经炎症升高和内源性阿片系统失调引起的。目前的结果支持昼夜节律紊乱与疼痛敏感性改变之间的关系。总之，我们观察到夜间昏暗的光线会诱发冷痛觉过敏和机械异常性疼痛，这可能是通过神经炎症升高和内源性阿片系统失调引起的。